Ansell (1989) maintained the availability of petteri should properly date from its first checklist citation (Gautun et al., 1985), not from its later formal description (Sicard et al., 1988), but Sicard et al. identified the holotype and museum in which it is stored and provided a differential diagnosis. According to Sicard et al. (1988), T. petteri is confined to the loop of the Niger River and is parapatric with T. gracilis, from which it differs in morphology, ecology, biochemistry, and physiology. In the same paper, they stated that T. petteri may actually be conspecific with angelus (from Gambia), although they acknowledged not examining the holotype of the latter, and they speculated that angelus and lacustris may prove to be the same but, because the type of the former is young and that of the latter is old, the relationship is difficult to demonstrate. Karyotype (2n = 18/19, FNa = 28) is distinctive compared with some other West African Taterillus; closest karyological relative is apparently T. tranieri (Dobigny et al., 2003).